(1) Field of the Invention
The present invention relates to a toner supply unit for toner supply to a developing unit provided in an image forming apparatus such as a copier, printer, facsimile machine or the like.
(2) Description of the Prior Art
In image forming apparatus such as copiers, printers, facsimile machines and the like, for charging the toner into an empty toner supply unit when the apparatus is set up, or when the toner in the toner supply unit has been used up after repeated operations of image forming and hence it has been determined that the residual toner held in the toner storage is almost finished, the most common scenario involves a special technician or the user, using a toner bottle or toner cartridge, and following the specified procedures re-supplying a predetermined amount of toner charged in the container.
However, there is a concern with these toner supply units that the surroundings will be contaminated by toner falling and scattering due to movements and impacts occurring when the unit is attached to and removed from the developing unit. Therefore, for these toner supply units, there are methods as follows which have been proposed in order to prevent the above problem from occurring at the joint between the toner supply unit and developing unit.
For example, a developing unit disclosed in Japanese Patent Application Laid-Open Hei 8 No. 76578, a shutter mechanism is arranged at the joining portion between the toner supply unit and the developing unit so that the shutter mechanism will be closed upon toner supply or upon its attachment and removal, whereby occurrence of surrounding contamination due to toner falling and scattering is prevented.
There is also a toner supply unit configuration in which an elastic sheet element, which is used to agitate the toner held in the toner supply unit, has an extension from its distal end so as to close the opening port for establishing connection from the bottom of the toner supply unit to the developing unit. In such a device, the extended part is pulled out from the opening when the agitator begins rotating for the start of use after attachment of the toner supply unit to the developing unit.
A device incorporating a shutter mechanism at the joining portion between the toner supply unit and the developing unit, as disclosed in Japanese Patent Application Laid-Open Hei 8 No. 76578, generally has a complex, bulky configuration needing more parts, hence result is unpreferable.
The device for closing the toner supply opening port in which an extension is provided from the distal end of the elastic sheet for toner agitation in the toner supply unit has a simple configuration, but a considerably strong force is needed in order to pull out the sheet end from the toner supply device when the toner supply unit is first operated. Further, since the distal end of the sheet after the removal will come into sliding contact with the inner wall of the toner supply unit, this may cause extra burden on the driving mechanism and may cause degradation of the toner characteristics resulting from frictional abrasion, hence result is unpreferable. It is true that toner falling occurring when the toner supply unit is mounted to the developing unit is prevented, but no consideration is given as to toner falling occurring when it is removed from the developing unit.
The present invention has been devised in view of the circumstances described above, and it is therefore an object of the present invention to provide a toner supply unit with a simple configuration which allows its easy attachment to and removal from the developing unit and can prevent toner falling and scattering upon the attachment or removal thereof.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a toner supply unit, including a toner supply container which is attachable to and removable from a developing unit for developing a static latent image formed on a photoconductor drum, and being configured so that toner is supplied to the developing unit through a slit-shaped opening port formed in the toner supply container when the toner supply container has been joined to the developing unit, is characterized in that a flexible element for covering the opening port in an openable and closable manner is provided so that, when the toner supply container is joined to the developing unit, the external force acted on the developing unit or toner supplying unit deforms the flexible element to release the opening.
In accordance with the second aspect of the present invention, the toner supply unit having the above first feature is characterized in that one longitudinal edge portion of the flexible element is fixed to the exterior wall of the toner supply container while the other side edge portion of the flexible element located on the free end side covers the opening port of the toner supply container in an openable and closable manner.
In accordance with the third aspect of the present invention, the toner supply unit having the above first feature is characterized in that the flexible element has elasticity and the deformation of the flexible element occurring when the toner supply container is joined to the developing unit is adapted to fall within the limit of its elasticity.
In accordance with the fourth aspect of the present invention, the toner supply unit having the above first feature is characterized in that the external force to be acted on the flexible element to release the opening port is obtained when the developing unit is moved from its retracted position to its proximal position with respect to the photoconductor drum.
In accordance with the fifth aspect of the present invention, the toner supply unit having the above first feature is characterized in that the edges at both ends on the free end side of the flexible element are cut inclined inwards toward the free end.
In accordance with the sixth aspect of the present invention, the toner supply unit having the above first feature is characterized in that the edges at both ends on the free end side of the flexible element are rounded on the free end side.
In accordance with the present invention, use of a flexible element that covers the opening port of the toner supply unit in an openable and closable manner, eliminates the necessity of a complex shutter actuating mechanism and a movable structure that can be opened and closed off, thus making it possible to markedly simplify the structure.
Further, the opening port can be released by the deformation of the flexible element when the toner supply container is joined to the developing unit, the operativity for attachment and detachment of the unit can be markedly improved without any need of providing a separate, driving source or extra parts.
In accordance with the present invention, the opening port can be released and closed off by simply providing a flexible element with its one edge portion fixed to the exterior wall.
In accordance with the present invention, it is possible to open or close the opening port using the elasticity of the flexible element itself. That is, when the developing unit and toner supply unit, which have been joined to each other, are separated one from another, the flexible element reverts itself back to the original state by its elasticity thus making it possible to shut off the opening port for toner supply.
In accordance with the present invention, since the joining operation of the developing unit and toner supply unit for releasing the opening port can be made at the same time the developing unit is set close to the photoconductor drum, the dedicated action for joining the developing unit and toner supply unit can be omitted, thus making it possible to improve the operativity and working performance upon attachment and removal.
When the flexible element has rectangular side ends, the flexible element may interfere (come into line contact) with the frame and other parts of the developing unit and is liable to damage itself when the developing unit is attached and removed. In accordance with this configuration of the present invention, since the edges at both ends on the free end side of the flexible element are cut inclined inward, the edges will come into contact with the frame of the developing unit over a smaller area (at points), thus making it possible to reduce impacts so that the flexible element becomes unlikely to break.
When the flexible element has rectangular side ends, the flexible element may interfere (come into line contact) with the frame and other parts of the developing unit and is liable to damage itself when the developing unit is attached and removed. In accordance with this configuration of the present invention, since the edges at both ends of the flexible element are rounded on the free end side, the edges will come into contact with the frame of the developing unit in a smaller area (at points), thus making it possible to reduce impacts so that the flexible element becomes unlikely to break.